Gas cutting torch for interchangeable tips

ABSTRACT

A gas torch in which a mixer assembly is joined to an interchangeable torch tip in a metal-to-metal seal made by a convexly coned end of the mixer assembly and a concavely coned end of the tip, each having two frustoconical portions separated by a recess. The frustoconical portions provide the metal-tometal seals; the high-pressure oxygen flows from the mixer assembly to and through the tip along the axis thereof and of the cones; fuel gas and low-pressure oxygen are mixed in the mixer assembly and flow by several passages to a chamber provided by the recesses between the frustoconical portions and from there by one or more passages to the tip outlet end where they surround the axial high-pressure oxygen outlet.

United States Patent GAS CUTTING TORCH FOR INTERCHANGEAB LE TIPS 4 Claims, 10 Drawing Figs.

US. Cl 239/4245, 239/4273 Int. Cl B05b 7/06 Field of Search 239/419,

[56] References Cited UNITED STATES PATENTS 2,829,709 4/1958 Mathews 239/4245 3.386.665 6/1968 lozzietal 239/416] Primary E.raminer-M. Henson Wood, J r. Assistant Examiner-Michael Y. Mar Attorney0wen, Wickersham & Erickson ABSTRACT: A gas torch in which a mixer assembly is joined to an interchangeable torch tip in a metal-to-metal seal made by a convexly coned end of the mixer assembly and a concavely coned end of the tip, each having two frustoconical portions separated by a recess. The frustoconical portions provide the metal-to-metal seals; the high-pressure oxygen flows from the mixer assembly to and through the tip along the axis thereof and of the cones; fuel gas and low-pressure oxygen are mixed in the mixer assembly and flow by several passages to a chamber provided by the recesses between the frustoconical portions and from there by one or more passages to the tip outlet end where they surround the axial high-pressure oxygen outlet.

PATENTED JUN 8 mm sum 2 0F 2 INVENTOIU R WM E0 2 NH mm s OZ Y E A W 5 0 m wm m LR w GAS CUTTING TORCH FOR INTERCHANGEABLE TIPS This invention relates to an improved gas torch for use in cutting operations. It also relates to an improved torch tip structure enabling more efficient use ofinterchangeable tips.

This invention may be considered as an improvement over the gas torch described and claimed in U.S. Pat. No. 3,386,665. The torch of that invention, while admirable in most respects, required careful machining of both the torch tip and the socket into which it fit. Otherwise, there tended to be leakage. This leakage tended to become accentuated when the torch tip was frequently changed, because the carefully machined end of the torch tip was exposed and tended to be damaged by the interchange. Such interchange might occur when one type of torch tip was replaced for a certain part of the operations with another torch tip; later the original tip might be reinstalled or a third torch tip used. Each one of these had a projecting end portion that required careful machining relative to its socket. and the very installation and removal sometimes tended to damage that end portion and to introduce inaccuracies, with consequent leakage.

The present invention enables the use of freely interchangeable torch tips made to a standard of accuracy that is not excessive in view of current manufacturing practice; there is no need to match the individual torch tips to an individual socket. Thus, freely interchangeable torch tips can be purchased after the unit has been in use, either to replace a worn or damaged torch tip with another one or to provide additional attachments. The torch tips are conically recessed at the end where they fit against the mixer assembly and so are protected from damage when they are off the torch assembly, yet an effective metal-to-metal seal is made with the mixer assembly on installation.

In addition, a new structure prevents leakage of high-pressure oxygen between the mixer assembly and the torch head body near the torch tip.

Other objects and advantages of the invention will appear from the following description of some preferred forms of the invention.

In the drawings:

FIG. 1 is a fragmentary enlarged view in elevation and in section of a torch head embodying the principles of the present invention, showing a torch tip installed and sealed to a mixer assembly.

FIG. 2 is a fragmentary view in section, further enlarged from a portion of FIG. 1, of the parts used for mating and sealing the mixer assembly with the torch head body, showing them before installation is completed.

FIG. 3 is a view similar to FIG. 2 with the mating completed.

FIG. 4 is a view in elevation and in section of a torch tip of the type used in the head of FIG. 1.

FIG. 5 is an end view of the upper end of the torch tip of FIG. 4.

FIG. 6 is an end view of the lower end of the torch tip of FIG. 4.

FIG. 7 is a view similar to FIG. 4 ofa modified type oftorch tip.

FIG. 8 is an upper end view thereof.

FIG. 9 is a lower end view thereof.

FIG. 10 is a view from the lower end of the inner member only of FIG. 7.

A torch of this invention may in many ways resemble the torch shown in U.S. Pat. No. 3,386,665, although a different structure may be used in many parts, because the particular invention herein applies only to the torch head portion.

As shown in FIG. 1, a torch head body 10 is provided with three sockets 11, 12, and 13 to receive three conduits I4, 15, and 16, namely a preheat oxygen conduit 14, a fuel gas conduit 15, and a high-pressure oxygen conduit 16. Preferably, the head body 10 is machined from brass to provide a main recess comprising a coaxial series of cylindrical recesses or chambers connected by steps. the recesses widening in diameter successively from a dead end 21 to an interiorly threaded open end 22. For example, and for purposes of illustration, there may be five successive principal steps, a first step 23, a second step 24, a third step 25, a fourth step 26, and a fifth step 27. between the dead end 21 and the open end 22, as the recess 20 gets successively wider. In this embodiment there are then six successive cylindrical portions or chambers 28, 29, 30, 31, 32 and 33. The body 10 is also bored to provide a passage 34 connecting the low-pressure oxygen conduit 14 to the first chamber 28 adjacent the dead end 21, a passage 35 connecting the fuel gas conduit 15 with the third cylindrical chamber 30, and a passage 36 connecting the high-pressure oxygen conduit 16 to the fifth chamber 32.

A removable mixer assembly 40 fits into the body 10. The mixer assembly 40 may be designed for use with low-pressure gases or for acetylene gas, there being some modifications in the form thereof but none which affect the present invention. Therefore, the mixer assembly 40 shown here is generally like that of the low-pressure mixer assembly shown in FIG. 5 of U.S. Pat. No. 3,386,665, by way ofexample.

The mixer assembly 40 may comprise three members: a seat member 41, a valve member 42, and a venturi member 43. The seat member 41 has a deep cylindrical recess 44 and its outer surface has three successively wider generally cylindrical portions 45, 46, and 47 joined by successive shoulders 48 and 49, and terminates in a generally conical nose or projecting end 50. An inner end wall 51 of the seat member 41 seats against the first step 23 of the body 10, and its cylindrical portion 45 fits rather snugly into the body's cylindrical portion 29. The first shoulder 48 of the seat member 41 is preferably spaced away from the third step 25 of the body 10, and the second shoulder 49 is preferably spaced well away from the fourth step 26. Between the cylindrical portion 45 of the seat member 41 and the cylindrical portion 30 of the body 10 is an annular chamber 52 into which the fuel gas passage 35 opens; and between the cylindrical portions 46 and 32 is an annular chamber 53 connected with the high-pressure oxygen conduit 36. Between the chambers 52 and 53, an O-ring 54 is carried in a groove 55 to seal against the wall 31 and prevent leakage between the chambers 52 and 53.

An important feature of the invention is the seal between the seat member 41 and the body 10 adjacent the shoulder 49. For this purpose, instead of being provided with a flat radial shoulder or a conical one, the fourth step 27 of the body 10 is provided with an annular spur 56 (see FIGS. 2 and 3) which can be swaged outwardly by pressure. The seat member 41 is provided not only with its flat shoulder 49 but also with a step 57 and a conical recess 58 undercutting the shoulder 49 and leading directly inwardly from the step 57. The result is that when the seat member 41 is driven into the body 10 from the position shown in FIG. 2 to the position shown in FIG. 3, the spur 56 is swaged into the conical recess 58 and forms a very tight metal-to-metal seal. Upon disassembly, the spur 56 is restored to its initial shape.

The seat member 41 has a long cylindrical recess 60 and a seat 61 projecting up from an annular end wall or shelf 62. The valve member 42 fits inside the cylindrical wall 60 and has an annular projection 63 resting on the shelf 62. The valve member 42 has an upwardly projecting sleeve portion 64 having openings 65 therethrough which together with openings 66 through the seat member 41 provide a passage from the annular chamber 52 into a mixing chamber 67. The venturi member 43 has a central conical passage 68 leading to a central axial passage 69 that goes into the chamber 67 and therefore conducts the low-pressure oxygen from the chamber 28 to the mixing chamber 67, where the fuel gas is mixed with the low-pressure oxygen. A central axial passageway 70 through the valve member 42 leads from the mixing chamber 67 toward the seat 61, and the valve member 42 is also provided with a flaring passage 71 at its lower end which cooperates with the seat member 61 to provide a restriction orifice venturi-type structure conducting the mixed gas into a recess 73 above the shelf 62. It may also be noted than an O-ring 74 may be provided to seal the chamber 28 from the chamber 52, the O-ring being carried in a recess 75 provided at the upper end of the member 43.

The present invention is not particularly concerned with the parts so far described, but they have been necessary to explain the environment of the invention. In the present invention the most pertinent part of the mixer assembly 430 is the nose portion 50 at the lower end thereof. Two frustoconical portions 80 and 81 of the nose 50 are separated from each other by a recessed portion 82 which may provide a flat shelf 83, although that is not essential. The recessed portion 82 may be at least partly provided by a screw thread portion 84 to which a withdrawal tool may be attached when it is desired to retract the mixer assembly 40 from the body 10. The frustoconical portions 80 and 81 are part of the same cone surface. The mixture of fuel gas and low-pressure oxygen is conducted by a series of passages 85 between the shelf 62 and the shelf 83. The high-pressure oxygen in the annular chamber 53 is conducted therefrom by a generally radially extending passageway 86 to a central axial passageway 87 having an outlet end 83.

While many different types of torch tips may be used, two are given by way of example, and, so far as the present invention is concerned, the most important parts of these torch tips are identical, so that the tips can be made interchangeable. Thus, a torch tip 90 is shown in FIGS. 4 through 6, and a torch tip 120, is shown in FIGS. 7 through 10, and both of them mate in the same way with the nose 50. For this purpose, they are both provided with two frustoconical portions 91 and 92 that are separated from each other by a recessed portion 93 and since all of these portions are concentric. they all lie around a central axial passageway 94 for the high-pressure oxygen. There may be an annular recess portion 95 adjacent the inner end of the high-pressure oxygen conduit 94. This conduit 94 generally tapers into or is stepped into a smaller diameter high-pressure oxygen passage 96 which is also axial and which terminates at an outlet end 97. So far as these features are concerned, the two tips 90 and 120 are substantially identical.

Moreover, the tips 90 and 120 are substantially identical in that at a shelf portion 98 provided by the recessed portion 93 each of them leads into a series of passageways 99 or 99a, which from that end are substantially identical. In the torch tip 90 ofFlG. 4, six of the passages 99 are shown, and they extend in agenerally conical direction toward the tip end 100 and they each are stepped into or tapered into narrower diameter passages 101 which are disposed in a ring surrounding the axial passageway 97.

The torch tip 90 is provided with an upper cylindrical wall 102 which is stepped at 103 into a smaller diameter cylindrical wall 104. A securing nut 110, shown in FIG. 1, is used to hold any and each of the torch tips 90, 120, etc., in place. The nut 110 has an outer threaded portion 111 which threads into the threads 22 on the body 10. The inner portion of the nut 110 is provided with a cylindrical wall 112 which is approximately of the same diameter as the wall 104 and is stepped outwardly by a step 113 to a larger diameter cylindrical portion 114. The portion 114 snugly encircles the wall 102 and the shoulder 113 abuts the shoulder 103 and therefore forces the torch tip 90 to move up toward the mixer assembly 40. When it does this, the frustoconical portions 91 and 92 approach the frustoconical portions 80 and 81 of the nose 50 and eventually engage these portions and make a metal-to-metal seal with them. When they do so, the recessed portions 84 and 93 cooperateto provide an annular chamber 115, so that it is not necessary for the passages 85 and the passages 99 to be aligned with each other, since the passages 85 lead into the annular chamber 115, and the passages 99 lead out from it. Therefore, the tip 90 and nose 50 can be sealed together without concern for alignment of the passages 85 and 99. Similarly, the central passage 87 for the oxygen is sealed off from the passages 85 and 99 by the frustoconical portions 80 and 91 but it is joined to the central axial passage 94 of the torch tip by a smaller annular chamber 116 provided by the recessed portion 95.

An important feature of this invention is that the interchangeable torch tips 911, 120, etc., do not have any projecting seat portion. instead, their seating portions 91 and 92 are concave into their body, so that they are unlikely to be damaged by any normal handling and can, in fact, stand rather rough handling and still not be damaged because in order to damage them a foreign article must get inside. This is in contrast with the former torch tips in which the seat portions projected out convexly. In this invention, the only convex portion is the nose 51) of the mixer assembly 40, which remains well protected at all times. The nut is easily loosened for replacement and for example, the torch tip 90 may be replaced with the torch tip 120.

The torch tip 120 has its passages 99a very short and leading into an annular passageway 121, provided by making the torch tip 100 of two members 122 and 123 which are held together when the device is in place. Thus the upper and inner member 122 has an outer periphery 124 the same size as the wall 102, and the lower and outer member 123 has at its upper end an outer periphery 125 of the same size, to fit inside the portion 114 ofthe nut. The upper member 122 has a shoulder 126 and a short cylindrical portion 127, which mate with an end wall 129 and a short cylindrical portion 129 of the lower member 123. The lower member 123 has a shoulder 130 that rests on the shoulder 113 of the nut and leads onto a cylindrical wall 131 the same size as the wall 104 and fitting into the bore 112 ofthe nut 110. The inner member 122 is provided with a series of semicircular grooves 132 around a lower portion thereof which serve, in effect, to define passages near the end of the torch tip. The end wall 134 of the inner member 122 is recessed from the end wall 135 of the outer member 123 for functional reasons well known in the art.

To reiterate, the important features ofthe present invention are the structure of the connection between the tips 90, 120, etc., and the nose 50 and the seal at 58 of the mixer assembly 40 in the body 10. These features make interchangeable torch tips practical and prevent leakage of the high-pressure oxygen into the mixture of fuel gas and low-pressure oxygen.

To those skilled in the art to which this invention related, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

We claim:

1. A gas torch comprising a mixer assembly and a plurality of interchangeable torch tips joined in a metal-to-metal seal provided by a convexly coned nose end of said mixer assembly and a concavely coned end of each tip,

each coned end having two corresponding frustoconical portions separated by an annular recess,

said mixer having a plurality of fuel gas passages leading into said recess and said tip having fuel gas passage means leading from said recess to an outer end of said tip, said mixer assembly having a central axial passageway for high-pressure oxygen at its said nose end and each said tip having a mating central axial passageway and a recess surrounded by one of said frustoconical portions to receive said nose end.

2. A gas torch, including in combination:

a torch head body having a recess and three gas passages leading into said recess at different locations, comprising a first gas passage for preheat low-pressure oxygen, a second gas passage for fuel gas, and a third gas passage for high-pressure oxygen,

a mixer assembly in said recess having mixing means connected to said first and second passages for mixing said fuel gas with said low-pressure oxygen and having a generally conical projecting outer nose end with two frustoconical surface portions of the same cone separated by an annular recess having an annular shoulder through which extend a plurality of passages for the mixture of fuel gas and low-pressure oxygen, said passages being connected to said mixing means, said mixer assembly also having a conduit for said high-pressure oxygen with an inlet portion connected to said third gas passage, and an axial central outlet at the extremity of said nose end and lying along the axis of the frustoconical portions. 5

a torch tip having an inlet end abutting said nose end and an outlet end and having a central axial conduit in line with said axial central outlet of said mixer assembly and extending the full length of said tip, for said high-pressure oxygen, said inlet end having a generally conical recess providing two frustoconical portions which mate with the frustoconical portions of said mixer assembly and providing with them a metal-to-metal seal between the conduits for the high-pressure oxygen and the passages for the mixture of said fuel gas and low-pressure oxygen and on both sides of said shoulder, said two frustoconical portions being separated by an annular recess cooperating with the annular recess of said mixer assembly to provide an annular chamber for reception of the mixture of fuel gas and low-pressure oxygen, said torch tip also having passage means leading from said annular recess at said inlet end to the outer end ofthe tip, and

means for holding said torch tip and said mixer assembly together to maintain said metal-to-metal seal.

3 The gas torch of claim 2 wherein said means for holding said torch tip and said mixer assembly together comprises an annular step on the torch tip and a correspondingly stepped tubular nut that is threaded into said body 4 The gas torch of claim 2 wherein said body is provided with a step on the outer side of said third gas passage provided with a sharp undercut to define a downwardly projecting annular spur and said mixer assembly has a radial step at the inner end of which is an annular flaring recess engaging said spur, so that tightening of said mixer assembly into said body forces said spur to swage out into said flaring recess and provide a metal-to-metal seal preventing leakage of said highpressure oxygen. 

1. A gas torch comprising a mixer assembly and a plurality of interchangeable torch tips joined in a metal-to-metal seal provided by a convexly coned nose end of said mixer assembly and a concavely coned end of each tip, each coned end having two corresponding frustoconical portions separated by an annular recess, said mixer having a plurality of fuel gas passages leading into said recess and said tip having fuel gas passage means leading from said recess to an outer end of said tip, said mixer assembly having a central axial passageway for high-pressure oxygen at its said nose end and each said tip having a mating central axial passageway and a recess surrounded by one of said frustoconical portions to receive said nose end.
 2. A gas torch, including in combination: a torch head body having a recess and three gas passages leading into said recess at different locations, comprising a first gas passage for preheat low-pressure oxygen, a second gas passage for fuel gas, and a third gas passage for high-pressure oxygen, a mixer assembly in said recess having mixing means connected to said first and second passages for mixing said fuel gas with said low-pressure oxygen and having a generally conical projecting outer nose end with two frustoconical surface portions of the same cone separated by an annular recess having an annular shoulder through which extend a plurality of passages for the mixture of fuel gas and low-pressure oxygen, said passages being connected to said mixing means, said mixer assembly also having a conduit for said high-pressure oxygen with an inlet portion connected to said third gas passage, and an axial central outlet at the extremity of said nose end and lying along the axis of the frustoconical portions, a torch tip having an inlet end abutting said nose end and an outlet end and having a central axial conduit in line with said axial central outlet of said mixer assembly and extending the full length of said tip, for said high-pressure oxygen, said inlet end having a generally conical recess providing two frustoconical portions which mate with the frustoconical portions of said mixer assembly and providing with them a metal-to-metal seal between the conduits for the high-pressure oxygen and the passages for the mixture of said fuel gas and low-pressure oxygen and on both sides of said shoulder, said two frustoconical portions being separated by an annular recess cooperating with the annular recess of said mixer assembly to provide an annular chamber for reception of the mixture of fuel gas and low-pressure oxygen, said torch tip also having passage means leading from said annular recess at said inlet end to the outer end of the tip, and means for holding said torch tip and said mixer assembly together to maintain said metal-to-metal seal.
 3. The gas torch of claim 2 wherein said means for holding said torch tip and said mixer assembly together comprises an annular step on the torch tip and a correspondingly stepped tubular nut that is threaded into said body.
 4. The gas torch of claim 2 wherein said body is provided with a step on the outer side of said third gas passage provided with a sharp undercut to define a downwardly projecting annular spur and said mixer assembly has a radial step at the inner end of which is an annular flaring recess engaging said spur, so that tightening of said mixer assembly into said body forces said spur to swage out into said flaring recess and provide a metal-to-metal seal preventing leakage of said high-pressure oxygen. 